Abstract:

The spatial pattern of the population was an important method to study the interaction of plant population and the relationship between the population and the environment. Reaumuria soongarica was the main species in arid region of Loess Plateau. Knowledge on the spatial pattern of R.soongarica can improve our understanding on adaptive characteristics of shrub to different slope aspects. Based on the field investigation, R.soongarica population spatial distribution pattern and its correlation were analyzed in different slopes by using Ripley K function method of spatial point pattern analysis of Gaolan County, Gansu Province, China. The spatial position of each R.soongarica individual in 10 m×10 m study plot was determined in different slope aspects. The results showed that R.soongarica population was at the rising stage, and its distribution had significant differences in different slopes. Age class I and II individuals of R.soongarica population showed a significant aggregation distribution on the small scale, and clump intensity gradually weakened with the increase of age class and space scale, and finally tended to a random distribution in south and west south slope aspects. In west and northwest slope aspects, the distribution pattern of all levels R.soongarica individuals were dominated by random distribution due to the growth of a large number of Ajania achilloides and Stipa breviflora caused by suppression and interspecific competition. In different slope aspect, R.soongarica populations between class I and II individual showed a negative correlation in small scale, but with scale increasing the correlation degree decreased. The relationship between class I with II and Ⅲ with Ⅳ individuals had negative correlation significantly. There was no significant relationship between the age III and IV, which showed that the individual with similar age was independent in spatial distribution. In the arid region of the Loess Plateau, the main influence factors of R.soongarica population distribution were its own biological and ecological characteristics, and the influence of microhabitats was also very important. This paper could provide technical support for the control of soil erosion in Gansu Province.

Key words: Times New Roman", ,serif, Loess Plateau')">">Loess Plateau, Reaumuria songarica population, age-class structure, point pattern, slope aspects